様々なグラム陽性細菌におけるフラビンベースの細胞外電子伝達機構
Samuel H Light1, Lin Su2,3, Rafael Rivera-Lugo1
1Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.
Nature
|September 14, 2018
まとめ
Listeria monocytogenesは,成長と生存のために新しいフラビンベースの細胞外電子伝送 (EET) システムを利用しています. このメカニズムは 既知の経路とは異なり 特定の遺伝子やフラビンを含み 微生物のコミュニティに影響します
科学分野:
- 微生物学と微生物生理学
- バイオ電気化学システム
- 遺伝学 と 分子 生物学
背景:
- 細胞外電子伝達 (EET) は微生物の生物電気化学的プロセスに不可欠ですが,ヘムベースのシステムを超えたメカニズムは十分に理解されていません.
- ミネラル呼吸するバクテリアは通常,複雑なヘムベースの電子伝送経路を使用します.
- 代替EET経路の存在とメカニズムの基礎は,ほとんど未知のままです.
研究 の 目的:
- 食物媒介の病原体Listeria monocytogenesにおける細胞外電子伝達のメカニズムを解明する.
- 新しいフラビンベースのEETシステムの遺伝的基礎と主要成分を特定する.
- 微生物コミュニティにおけるこのEETメカニズムの生理学的役割と流行を調査する.
主な方法:
- 細胞外鉄還元酵素の活性が低下したL.monocytogenes変異体を特定するための遺伝子スクリーンを進める.
- EETに責任を持つ8基因の場所の特定と特徴付け
- 特定の遺伝子や分子 (NADH脱水素酵素,キノンプール,フラボタンパク質,フラビンシャトル) の役割を決定するための生化学的測定と遺伝子分析.
主要な成果:
- 特殊なNADH脱水素酵素をコードし,フラビンベースのEETを促進する8基因の新型ロカスがL. monocytogenesで特定されました.
- このシステムは,電子を異なるキノンのプールにチャネルし,鉄や電極のような受容体に電子を転送するために細胞外フラボタンパク質とフラビンシャトルを使用します.
- EETの活性化は,非発酵性の炭素源での成長をサポートし,EETの変異体はマウスの腸に競争的欠陥を示します.
結論:
- L.monocytogenesは,ヘムベースのシステムとは異なるフラビン依存のEETメカニズムを使用し,外部受容体への電子転送を可能にします.
- このフラビンベースのEETシステムは,特定の炭素源の利用に不可欠であり,宿主に関連した環境において競争上の優位性をもたらします.
- 特定されたEET遺伝子とメカニズムは,Firmicutes族全体に広く存在し,電気性の細菌にとって広範な生態学的および病原学的関連性を示唆しています.
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